Bio 5.2 Respiratory System PDF

## Unit 5: The Respiratory System The Respiratory System supplies the body with oxygen for **energy production**. Without oxygen, the body would shut down in minutes. The Respiratory System works closely with the **Circulatory System** to allow oxygen to get to all the cells in the body, and for...

## Unit 5: The Respiratory System The Respiratory System supplies the body with oxygen for **energy production**. Without oxygen, the body would shut down in minutes. The Respiratory System works closely with the **Circulatory System** to allow oxygen to get to all the cells in the body, and for **carbon dioxide** to be removed. ### Four processes: 1. **Breathing** *(two processes)*: - **Inspiration**: bringing air **into** the lungs. - **Expiration**: expelling CO₂ **out of** the lungs. 2. **External Respiration**: - Exchange of gases between the **inside the lungs** and the **blood**. 3. **Internal Respiration**: *(alveoli)* - Exchange of gases between the **blood** and **body tissues/cells**. 4. **Cellular Respiration**: mitochondria - Production of ATP **within cells** - FORMULA: C₆H₁₂O₆ + O₂ → CO₂ + H₂O + ATP ### Breathing: Inhalation and Exhalation Breathing is a **closed system**, meaning that it is or can be completely **sealed off** from the rest of the body and the **outside environment**. This helps prevent things from entering the delicate respiratory system so as not to **damage it**. #### Inhalation: A step-by-step guide... 1. The concentrations of CO₂ and H⁺ are the **primary stimuli** that cause us to breathe. 2. When [CO₂] and [H⁺] are **too high**, the breathing center in the **brain** is stimulated. 3. A **nerve impulse** is sent from the Medulla Oblongata to the **ribs and diaphragm**, which are attached to the lungs. 4. The diaphragm **contracts and lowers** while the intercostal muscles of the ribs **contract** to **raise the ribs**. 5. These actions **increase the size** of the chest cavity, thereby **increasing its volume**. 6. At the same time, there is a decrease in **air pressure** due to a **partial vacuum** being created in the lungs. 7. The air pressure in the lungs is reduced so much that air **rushes in** from **outside** to **rebalance the pressure**. ***NOTE:*** Air enters because the lungs have already opened. The air does not force the lungs open. The dramatic decrease in air pressure "sucks" air into the lungs. This is why it is said that we breathe through **negative pressure**. The lungs themselves have no muscles, so it is only this **pressure differential** that causes air to enter them. (Remember: FLOW TO LOW!) * ↑ volume (inhalation) ↓ volume (exhalation) * ↓ pressure ↑ pressure #### Exhalation: Another step-by-step guide... 1. When the lungs are full, **stretch receptors** in alveoli are stimulated. 2. These receptors notify the **Medulla Oblongata** and it stops sending impulses to the ribs and diaphragm. 3. The diaphragm and ribs muscles **relax** and return to **resting state**. 4. This **decreases** the size of the chest cavity, therefore **decreasing volume** and **increasing air pressure**. 5. Now that the air pressure is **higher** than the outside air pressure, air is forced **out** of the lungs. In addition to the Respiratory Center in the Medulla Oblongata, there are other receptors that can respond to stimuli: * **Carotid bodies** - in the carotid artery * **Aortic bodies** - in the aorta These respond to high concentration of **hydrogen ions (H⁺)** but can also respond to levels of **carbon dioxide** in the blood. ### Gas Exchange: General Rules * When CO₂ diffuses into the blood from the tissues, 9% is held in solution as dissolved CO₂. * 27% attaches to hemoglobin to form **carbaminohemoglobin (HbCO₂)**. * The remaining 64% reacts with **water** to form **bicarbonate ion (HCO₃^-)** and **hydrogen ion (H⁺)**: _{*CO₂ + H₂O → HCO₃^- + H⁺*} ### External Respiration: From the Lungs to the Blood * High concentrations of O₂ in alveoli of the lungs cause the **diffusion** of O₂ into blood stream along its **concentration gradient**. * In the blood stream, O₂ joins with **reduced hemoglobin (Hb)** to form **oxyhemoglobin (HbO₂)** and _H⁺_. * H⁺ ions are **picked up** by **bicarbonate ion (HCO₃^-)** to temporarily form **carbonic acid** which breaks down immediately to produce (64%) CO₂ + H₂O, which diffuses into the alveoli of the lungs to be **exhaled**. * **Dissolved CO₂** (9%) that is carried in the blood plasma diffuses into alveoli of the lungs to be exhaled. (27%) **Carbaminohemoglobin** breaks down into CO₂ and hemoglobin, CO₂ diffuses into the lungs and is exhaled while hemoglobin **picks up** oxygen. This means that O₂ attaches to hemoglobin **in two contexts**: reduced hemoglobin and carbaminohemoglobin. * O₂ + HHb → HbO₂ + H⁺ * O₂ + HbCO₂ HbO₂ + CO₂ ____ ***IMPORTANT NOTES:*** * H⁺ ions **do not accumulate** in the blood surrounding the lungs because as soon as it is released from hemoglobin, it combines with HCO₃^- to form **carbonic acid** which breaks down right away (assisted by **carbonic anhydrase**) into CO₂ and H₂O. These diffuse into the lungs and are expelled. In this way, HCO₃^- **acts as a buffer** at the lungs to keep pH **stable**! * **Hemoglobin also acts like a buffer**: it serves as a carrier for O₂, CO₂, and H⁺, so it **acts like a buffer** at the **tissues of the body**! ### Internal Respiration: Blood -> Tissues Remember... * 9% of CO₂ diffuses from the tissues of the body into the blood stream and travels as dissolved CO₂. * 27% of CO₂ binds to hemoglobin to form carbaminohemoglobin. * 64% of CO₂ reacts with water to temporarily form **carbonic acid (H₂CO₃)** which breaks down right away to bicarbonate ion (HCO₃^-) and H⁺ (facilitated by **carbonic anhydrase**). * CO₂ will diffuse out of the tissues with its concentration gradient: 9% will remain dissolved in blood, 27% will bind to hemoglobin, and 64% will react with water in the blood. * Most of the released H⁺ from the carbonic acid reaction reacts with **oxyhemoglobin (HbO₂)** at the tissues to form reduced hemoglobin (HHb). This causes the release of O₂, which can diffuse with its concentration gradient into the tissues. The remaining hemoglobin that does not bind H⁺ will bind **CO₂** (27%). * The blood leaving the tissues now contains **large quantities** of carbaminohemoglobin and reduced hemoglobin. The blood also contains large amounts of **HCO₃^-**. No further changes occur until the blood reaches the lungs. **Be sure you understand all the equations shown in the diagrams above. Be able to name all the molecules and identify the equations as external respiration (It's easy if you just reverse the equations from one type of respiration).** ### External: <br> Oxyhemoglobin 1. O₂ + Hb = HbO₂ Carbaminohemoglobin 2. HbCO₂ = Hb + CO₂ Reduced Hemoglobin 3. HHb = Hb + H⁺ Bicarbonate Ion Carbonic Acid 4. HCO₃^- + H⁺ = H₂CO₃ = CO₂ + H₂O <br> HHb + O₂ → HbO₂ + H⁺ HbCO₂ → Hb + CO₂ <div align="center"> <img src="https://cdn.pixabay.com/photo/2017/08/08/13/40/arrow-2629693_1280.png" width="60" height="30"> <img src="https://cdn.pixabay.com/photo/2017/08/08/13/40/arrow-2629693_1280.png" width="60" height="30"> </div> <div align="center"> diffuse out of lung diffuse out of lung (27%) </div> ### Internal: <br> HbO₂ + H⁺ → HHb + O₂ HbCO₂ + O₂ → HbO₂ + CO₂ <br> <div align="center"> <img src="https://cdn.pixabay.com/photo/2017/08/08/13/40/arrow-2629693_1280.png" width="60" height="30"> <img src="https://cdn.pixabay.com/photo/2017/08/08/13/40/arrow-2629693_1280.png" width="60" height="30"> </div> <div align="center"> to tissue from tissue form tissue to tissue </div> <div align="center"> CO₂ + H₂O (64%) → H₂CO₃ → HCO₃^- + H⁺ (64%) diffuse out (27%) </div> This is a summary of the text in the provided image. No images or links to images are included as requested.